The TH9 antibody monoclonal antibody specifically binds to CD59, a 21 kDa glycosyl-phosphatidyl inositol-anchored cell-surface glycoprotein of the Ly-6 superfamily. CD59 is expressed by many types of non-hematopoietic cells. In the rat hematopoietic system, CD59 has been detected on erythrocytes, monocytes, and some lymphocytes, but not on platelets. Soluble CD59 is found in body fluids and urine. CD59 is a complement regulatory protein that acts late in the complement cascade to prevent formation of the membrane attack complex (MAC). Therefore, CD59 is one of several proteins whose function is to protect host tissue from complement attack. Rat CD59 binds rat and human complement components and inhibits cytolysis mediated by complement from multiple species. CD59 has also been suggested to be a ligand for CD2 and to participate in T-cell costimulation.
The antibody was conjugated to BD Horizon™ BUV661 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 661-nm. BD Horizon Brilliant BUV661 can be excited by the ultraviolet laser (355 nm) and detected with a 670/25 filter and a 630 nm LP. Due to cross laser excitation of this dye, there may be significant spillover into channels detecting APC-like emissions (eg, 670/25-nm filter).
Due to spectral differences between labeled cells and beads, using BD™ CompBeads can result in incorrect spillover values when used with BD Horizon BUV661 reagents. Therefore, the use of BD CompBeads or BD CompBeads Plus to determine spillover values for these reagents is not recommended. Different BUV661 reagents (eg, CD4 vs. CD45) can have slightly different fluorescence spillover therefore, it may also be necessary to use clone-specific compensation controls when using these reagents.